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3T Prototypes put Safety First

02 August 2005 ...

Sprue Aegis is the life safety products manufacturer responsible for the innovative new FireAngel PS-101 Plug-In Smoke Alarm which is a consumer-fit, mains-powered smoke alarm, which overcomes the need for a replacement battery. It fits between a light socket and light bulb, and is designed to recharge automatically when the light is switched on. A key feature of the PS-101 is that the alarm can be tested using the existing light switch and reset in the same way in the event of nuisance alarms.

In testing and developing the Smoke Alarm, the audible resonance created when the alarm is raised needed to be emulated, but it was proving difficult to find a pre-production material that could replicate the desired sound. 3T produced SLS prototypes of the buzzer housings, and when tested and compared with the real mouldings, the results were very pleasing.

Stuart Hart, Senior Electronics Engineer at Sprue Aegis, said “We did some comparative measurements on one of the sample SLS buzzer housings and they were found to perform as well as the standard production housing.”

He continued, “The same piezo element was fitted to the sample as a standard buzzer housing using double sided adhesive tape; the complete buzzer was fitted into an EZ-212 circuit board. The circuit was forced into ‘self test’ and the peak sound level measured at 300mm from the front of the buzzer (all other test conditions being constant). The peak sound level was typically around 100dB for the original housing. This could vary by around one dB, but seemed generally to be fairly constant. A similar reading of 101dB was registered for the SLS housing. The sound output was very similar for the standard and SLS buzzer housings. Allowing for uncertainties in test conditions, the variation is less than can be accurately measured.”

Matt Quinn, Senior Product Designer at Sprue Aegis says “We are committed to developing a complete range of consumer-driven, innovative and high technology safety protection systems. Product innovation and development lies at the heart of our business and with 3T’s ongoing research and development into material capabilities and functionality of their SLS process, this is critical to our growth.”

Tim Plunkett, CEO of 3T says “Testing by analogy can provide a valuable insight into component performance in advance of component hardware being available. In this instance, Sprue Aegis tested the existing design in both production and prototype form to create the performance analogy that could then be applied to the new design.”

Further information on the FireAngel PS-101 Plug-In Smoke Alarm and to purchase online, visit

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